I think you'll find that just by looking at the pictures of intact RB's - it would seem they were more or less stationary on arrival at the roof.
What about the scenario that they did an almost successful emergency landing, the blades were stopped and then the roof collapsed?
From the reports out of the pub it was quite a time from first impact to the collapse. And also there was so far no report where the bodies of the crew were found, inside or outside the cabin?
Just my opinion